1. Field of the Invention
The present invention relates generally to the field of devices for dispersing heat generated within electric light sources, and more specifically to a housing surrounding a light source which receives a stream of air through conduits from an air conditioning duct to cool the light source, the housing having any suitable shape, preferably that of a frustum, and having three spaced apart lenses at its lower end, the bottom lens being frosted and the conduits being connected at the edges of the lenses to deliver cooled air between the lenses and through perforations in the top lens and into the housing for absorbing and carrying away heat and out through an exhaust vent.
2. Description of the Prior Art
There have long been light sources incorporating means for absorbing or dissipating heat generated by the source. These means have included housings for light sources containing fans, vent ports and insulation, as well as isolated, heat absorbing metal structures.
An example is that of Moore, U.S. Pat. No. 3,299,884, issued on Jan. 24, 1967. Moore teaches an air cooled lamp including a bulb and socket enclosed in an essentially cylindrical housing and attached to an electric cord. The housing also contains a lens, a double-propeller fan and an electric motor for driving the fan, which draws air into the housing through slots and passes it over the bulb and lens. A problem with Moore is that the circulated air is only at room temperature and thus can absorb only a minimal amount of heat. Another problem is that the fan can create an annoying buzz, vibrate the lamp and generate additional heat.
An alternative to the convection heat transfer of Moore is the examination light apparatus of Bodian, U.S. Pat. No. 3,348,036, issued on Oct. 17, 1967. Bodian discloses a metal body surrounding the lens for absorbing heat and then dissipating the heat from fins along its outer surface. A plastic insulating shell surrounds the metal body so that the apparatus can be handled. A problem with Bodian is that, once again, only room temperature air is provided for cooling the light. Another problem is that no means is provided for circulating the air, apart from a minimal natural draft caused by air temperature differences.
Sharp, U.S. Pat. No. 4,449,166, issued on May 15, 1984, recites a rectangular lighting fixture which is inserted as a panel into a drop ceiling. A central housing portion contains light bulbs, while a separate, perimetric portion delivers cooled air from an air conditioning duct into the room. The combined light fixture and air conditioning vent is intended to be both aestheticly pleasing and space saving. A problem with Sharp is that no provision is made for cooling the light source itself.
Wheeler, U.S. Pat. No. 4,546,420, issued on Oct. 8, 1985, teaches a light fixture for transmitting filtered light having a narrowed spectrum. Filter lenses absorb various wavelengths of the light before it leaves the fixture, causing the lenses to become very hot. To dissipate the heat, the lenses are staggered and placed in the path of an air stream from a fan inside the fixture. The air flows between the lenses and cools them. A problem with Wheeler, once again, is that the air circulated is room temperature air, with limited heat absorbing capacity. Also, the overall design of the fixture, for narrowing the spectrum, has few practical uses.
Moroi, U.S. Pat. No. 4,630,182, issued on Dec. 16, 1986, discloses an air-cooled arc lamp which, like Moore and Wheeler above, includes a fan and a cylindrical housing surrounding the lamp and fan. The fan draws air into the housing through side ports, over the reflector, out of a hole in the top of the reflector and blows that air out of the top of the housing. A problem with Moroi, as above, is that room temperature air is used to absorb and carry away heat. And, again, a fan can make an annoying sound and generate heat.
Vines, U.S. Pat. No. 4,734,835, issued on Mar. 29, 1988, teaches a mercury lamp contained in a housing including cooling fins and a vacuum induced air flow to dissipate heat and draw away poisonous vapors in the event the lamp explodes. A problem with Vines is that its usefulness is essentially confined to the peculiarities of the mercury lamp. A vacuum bottle is not suited to generating continuous cooling over a prolonged period of use. The heat fins are helpful but inadequate for proper heat dissipation.
Fisher, U.S. Pat. No. 4,600,979, issued on Jul. 15, 1986, recites a light fixture including a vertical metal cylinder containing the light source. An annular reflector surrounds the cylinder, there being a gap between the two, and an outer housing extends above the reflector. Air near the cylinder absorbs heat from the light source and rises through the gap and into the space between the reflector and the housing. Then the air cools and falls along the upper face of the reflector and escapes through holes at the reflector base. This air may rise to again surround the cylinder and repeat the cycle. A problem with Fisher, once again, is that only room temperature air is supplied. Also, only the minimal natural currents resulting from air temperature differences circulate the air.
Pietro, U.S. Pat. No. 4,858,089, issued on Aug. 15, 1989, is very similar to Fisher in that hot air rises through openings in the reflector and is trapped within an outer housing where it cools. Wimberly, U.S. Pat. No. 4,999,758, issued on Mar. 12, 1991, discloses a plastic housing, spaced apart from the sides of a light bulb for reduced housing temperature. Ivey, U.S. Pat. No. 5,021,932, issued on Jun. 4, 1991, teaches still another ventilator fan in a light source housing. Ivey adds the feature of a thermostat-controlled fan switch. Cartwright, U.S. Pat. No. 5,055,988, issued on Oct. 8, 1991, discloses a surgery lamp within a shroud having ventilating holes and chimneys to carry away heated air. For most of these, room temperature air and minimal air circulation are again problems.
It is thus an object of the present invention to provide a light source cooling apparatus which delivers a continuous stream of air to the light source which is below room temperature and therefore has greater heat absorbing capacity.
It is another object of the present invention to provide such an apparatus which receives the continuous stream of air from an air conditioning duct through two parallel air delivery conduits adjacently joined to a double intake funnel connected to the air conditioning duct and discharging the air stream through an exhaust conduit.
It is still another object of the present invention to provide such an apparatus which can be easily and inexpensively installed in most buildings and vehicles.
It is still another object of the present invention to provide such an apparatus which creates air circulation beyond natural drafts.
It is finally an object of the present invention to provide such an apparatus which is simple in design, reliable and inexpensive to manufacture.